Thirty-four years after the first atomic test in 1945—to the day and hour—a clap of sound like thunder echoed through the eastern part of the Navajo Nation, near Church Rock, New Mexico. On the morning of July 16, 1979, neighbors and mill workers woke to the collapse of the huge earthen dam at the United Nuclear Corporation Church Rock uranium mill. The accident released 1,000 tons of radioactive mill tailings—radium-laced sandy debris left over from the extraction and concentration of uranium—and 93 million gallons of acidic and radioactive wastewater into a deeply cut creek that flowed into the Rio Puerco. The waste flowed downstream at least 80 miles through the arid, rocky landscape past the homes of some 1,700 Navajo people.

That summer day in 1979 Native Americans awoke to the broader ecological impacts of uranium mining. Patches of radioactive hot spots were scraped only from the first five miles of the riverbed, and contamination problems remain to this day. The U.S. Geological Survey considers the Church Rock incident the largest accidental radioactive release in the United States. Earlier that year the nuclear accident at Three Mile Island power plant made national and international news; the Church Rock accident did not, even though it distributed more than three times (46 curies) the radiation levels of the Three Mile Island accident (13 curies). For Church Rock residents there was no state of emergency, no evacuation, and limited alternative water supplies.

The response to the Church Rock accident was not an anomaly. Native American miners—Navajo, Pueblo, and Hopi—had been working in underground uranium and vanadium mines since 1941 without the health precautions standard in other mines, such as pumping in fresh air for ventilation to dilute radon concentration. (Radon, a decay product of uranium, can cause lung cancer if inhaled.) Miners worked in dim underground mines using pneumatic drills that gouged holes in the rock for planting dynamite. After the explosion collapsed the ore vein, miners were often ordered back inside before the uranium and silica dust had a chance to settle. The dust swirled around them so thickly they could barely see to shovel the blasted ore into the carts. Trucks later took the raw ore to mills that used sulfuric acids and alkaline chemicals to leach out the uranium and concentrate it into yellowcake for use elsewhere. Left behind in ponds and unmarked piles was the radioactive debris. The nearby Nevada Test Site, a nuclear-weapons testing facility, produced its own hazards, which the prevailing winds then blew across the Navajo lands. The uranium mined from these lands fueled the nuclear reactors at Hanford Nuclear Reservation in Washington State, which made plutonium for nuclear weapons, and later fueled civilian nuclear-power plants.

Nuclear-industry spokespersons, U.S. government agencies, and nuclear scientists often state that no one has ever been killed or harmed by the operations of a civilian nuclear-power plant in the United States. For example, the Department of Energy website and its brochures state that U.S. utilities have operated commercial nuclear-power plants since 1957 and “during this time, no one in the United States has died or been injured as a result of operations at a commercial nuclear power plant.” Yet by the time uranium mining finally petered out in the early 1980s, hundreds of Indian miners had died from lung diseases and cancers that physicians and secret U.S. Public Health studies linked to the miners’ uranium exposure. The Navajo Nation was littered with abandoned, open, and radon-emitting former mine sites—at least 1,032 of them. The United Nuclear Corporation mill and adjacent mine had become Superfund sites, and the cancer rate had doubled on Navajo lands. In addition, until 1980 untreated water was discharged from the mining and milling companies into the Rio Puerco at a rate of 2.8 billion gallons per year. Mine waste was dumped in piles where children played until the 1990s.

A multiagency remediation of the landscape begun in 2008 is now in its final year. To date the Environmental Protection Agency (EPA) and Navajo Nation EPA has removed 14 homes, 20 other structures, and 18 residential yards because of contamination. Also, 38 water wells, streams, and other water sources were found to exceed health limits for radionuclides. Written warnings in both Diné (Navajo) and English are posted on wells whose water is unsafe to drink.